CHAPTER 20 CLOCK MONITOR
Preliminary User’s Manual U16315EJ1V0UD
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20.4 Operation of Clock Monitor
This section explains the functions of the clock monitor. The start and stop conditions are as follows.
<Start condition>
When bit 0 (CLME) of the clock monitor mode register (CLM) is set to operation enabled (1).
<Stop condition>
•
In STOP mode and during the oscillation stabilization time
•
During the oscillation stabilization time after reset is released
•
When the X1 input clock is stopped by software (when MSTOP = 1 or MCC = 1)
•
When the Ring-OSC clock is stopped
Remark
MSTOP: Bit 7 of the main OSC control register (MOC)
Table 20-2. Operation Status of Clock Monitor (When CLME = 1)
CPU Operation Clock
Operation Mode
X1 Input Clock Status
Ring-OSC Clock Status
Clock Monitor Status
Oscillating
STOP mode
Stopped
Stopped
Note
Oscillating
RESET input
Stopped
Note
Stopped
Oscillating
Operating
X1 input clock
HALT mode
Oscillating
Stopped
Note
Stopped
STOP mode
RESET input
Stopped
Oscillating
Stopped
Oscillating
Operating
Ring-OSC clock
HALT mode
Stopped
Stopped
Note
The Ring-OSC clock is stopped only when the “Ring-OSC can be stopped by software” is selected by a
mask option. If “Ring-OSC cannot be stopped” is selected, the Ring-OSC clock cannot be stopped.
The clock monitor timing is as shown in Figure 20-3.